**Your
answer to Q60: **Sorry, your answer is **not** correct. Be
sure you do not confuse medium motion with wave motion.

Help: *Fundamentals of
Sound, *Secs. 1-D, 1-G.

Or would you like a HINT ?

Return to Question
60

**Hint
for Question 60:** The medium motion and the wave motion are the ideas in
question here. What is point B doing while the wave goes by?

Return to Question
60

**Your
answer to question 60**: Congratulations, your answer is** correct!**

If you like, you can compare
your answer to the "official" correct answer.

Return to Question 60

**Correct
answer to Q60: **While a wave moves to the right, point B is moving up to
the maximum displacement, then back down to zero, and then to a negative displacement,
and finally back to equilibrium. That is a complete cycle, carried out in one
period, and describes the **medium** motion. b) is the correct answer.

Return to Question 60

**Your
answer to question 65: **Sorry, your answer is **not** correct.
You should look up the definition of wavelength.

Help: *Fundamentals of
Sound, *Secs. 1-D, 1-G.

Or would you like a HINT ?

Return to Question
65

**Hint for question 65: **Wavelength
is the distance between two adjacent crests of a wave, as, for example, the
peak to peak distance.

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**Your
answer to question 65: **Congratulations, your answer is** correct!**

If you would like, you can compare your answer to the "official" correct answer.

Return to Question
65

**Correct
answer to Question 65: **The distance from one peak to the next is 2 feet.
You can also take the distance from any one point to the next precisely similar
point, for example, from a zero where the wave is going up, to the next zero
where it is again going up and has completed one cycle in space.

Return to Question 65

**Your
answer to Question 70**: Sorry, your answer is **not** correct.
You should look up the definition of amplitude.

Help: *Fundamentals of
Sound, *Secs. 1-D, 1-G.

Or would you like a HINT ?

You should try to work it out on your own, but if you insist on reading it the correct answer is here.

Return to Question
70

**Hint for question 70: **Amplitude
is the distance from the zero position (equilibrium or at-rest position) of
any point to the point where is at a maximum distance away from equilirium.

Return to Question
70

**Your
answer to question 70: **Congratulations, your answer is** correct!**

If you like, you can compare
your answer to the "official" correct answer.

Return to Question 70

**Correct answer to question 70: **The
amplitude is 1 foot. This is the distance from the at-rest position to the position
of a peak of a wave. The correct answer is a).

Return to Question
70

**Your
answer to question 75: **Sorry, your answer is **not **correct.
You should look up the definition of period.

Help: *Fundamentals of
Sound, *Secs. 1-D, 1-G.

Would you like a HINT?

You should try to work out
the answer on your own, but if you insist on reading it the correct
answer is here.

Return to Question 75

;

**Hint for question 75: **The
period is the time for one complete cycle.

Return to Question 75

**Your
answer to question 75: **Congratulations, your answer is **correct!**

If you like, you can compare your answer to the "offical" correct answer.

Return to Question
75

**Correct
answer to question 75:** The period is the time for one complete cycle.
Follow the point B as is moves up and then back down. It reaches its lowest
point after 1.5 s, but that is not yet one complete cycle; it must next return
back to its starting position, which it does by 2 seconds. The period is thus
2 seconds and the correct answer is d).

Return to Question
75

**Your
answer to question 78: **Sorry, your answer is **not** correct**.**
You should look up the definition of frequency.

Help: *Fundamentals of
Sound, *Secs. 1-D, 1-G.

Or would you like a HINT?

You should try to work out
the answer on your own, but if you insist on reading it, the correct
answer is here.

Return to Question 78

**Hint for question 78: **The
frequency is the number of cycles occurring in one second (Hertz). Examine how
many cycles (or fractions of a cycle) point B has undergone after one second.

Return to Question
78

**Your
answer to question 78**: Congratulations, your answer is **correct**!

If you like, you can compare
your answer to the "official" correct answer.

Return to Question 78

**Correct answer to question 78: **After one
second, point B has undergone only half a cycle, so that the the frequency is
0.5 Hertz. One can also use* f*=1/*T *= 1/(2 s) = 0.5 Hz.

Return to Question
78

**Your
answer to question 80: **Sorry, your answer is **not** correct. You
should look up the definition of wave velocity.

Help: *Fundamentals of
Sound, *Secs. 1-D, 1-G.

Or, would you like a HINT?

You should try to work out the answer on your own, but if you insist on reading it, the correct answer is here.

Return to Question
80.

**Hint for question 80: **Wave
velocity is the distance traveled divided by the time to travel that distance.
Pick a point and see how far it travels in, say, 1 second.

Return to Question
80.

**Your
answer to question 80: **Congratulations, your answer is **correct**!

If you like, you can compare your answer to the "official" correct answer.

Return to Question
80.

**Correct
answer to question 80: **The wave travels one wavelength in one period. Thus
the wave velocity (distance over time) is 2 ft/2 s = 1 ft/s. Another way to
do this is to use the formula velocity = frequency x wavelength = 0.5 Hz x 2
ft = 1 ft/s.

Return to Question 80.

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